Oil or gas wells are often surveyed to determine one or more geological, petrophysical, geophysical, and well production properties (“parameters of interest”) using electronic measuring instruments conveyed into the wellbore by an umbilical such as a cable, a wireline, slickline, drill pipe or coiled tubing. Tools adapted to perform such surveys are commonly referred to as formation evaluation tools. These tools use electrical, acoustical, nuclear and/or magnetic energy to stimulate the formations and fluids within the wellbore and measure the response of the formations and fluids. The measurements made by downhole instruments are transmitted back to the surface. In many instances, multiple trips or logging runs are needed to collect the necessary data.
As is known to those versed in the art, certain tools collect a first set of data while in a substantially concentric position relative to the wellbore and collect a second set of data while in a substantial eccentric position relative to the wellbore. Conventionally, the position of tools on an umbilical are static or fixed. Thus, two or more logging runs may be required to collect the two types of data, even though one tool can collect both types of data. As is also known in the art, certain logging runs can utilize a dozen or more different measurement tools in a single package. Each of these tools may require a different position relative to the wellbore (e.g., radial position relative to the wellbore axis) and/or different physical orientation relative to one another.
Merely by way of illustration and not to limit the scope and application of the present invention, reference is made to a nuclear magnetic resonance (“NMR”) tool such as that described in U.S. patent application Ser. No. 09/997,451 (“'451 Application”) having the same assignee as the present application and the contents of which are fully incorporated herein by reference. The '451 Application describes an NMR tool that may be operated in a centralized position in a small diameter borehole and in a decentralized position in a large diameter borehole. The NMR tool is merely representative of a number multi-purpose tools that, conventionally, are re-set in different radial positions (e.g., alignment, orientation, etc.) at the surface in order to perform different tasks downhole (e.g., collect different types of data).
The present invention addresses these and other drawbacks of conventional well tools.